Gas Turbines and Filters

A gas turbine is a type of engine that creates thrust or rotation by exploiting a continuous movement of hot gas. It is distinct from an internal combustion engine, which captures the force of a small aerosol explosion inside a tube and using the force of the expanding gas to drive a piston. A gas turbine is light and operates more efficiently at a continuous speed. It is one solution for driving a rotary kiln.

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A gas turbine does not require alternating pistons to create thrust, but creates continuous thrust through the constant motion of expanding gas through a spiral called a turbine. Because the turbine spins rather than moves in a cycle, its motion is constant. It drives its load with a consistent motion that takes time to accelerate and slow down.


Internal combustion engines are preferred for cars because the force can be precisely controlled. The force occurs directly inside the combustion chamber and its power can change in less than a second. Because cars with internal combustion engines can make sudden changes in speed, they are sometimes safer and more responsive than cars with turbine engines.


Turbine engines are highly efficient and weigh much less than engines with pistons. This makes them ideal where space and weight are issues. They might deal with extremely high temperatures, and so safeguards against heat stress are important parts of a turbine engine. This also means that turbine engines must work within exact specifications.


High speed rotation is ideal for aircraft, where air in a jet must be compressed and then rammed through the turbine to create both mechanical power and thrust. A rotary kiln does not need high speed rotation, but it does need to maintain the slow rotation of a large tubular container at a consistent pace, sometimes for days. A small turbine can rotate a large kiln by modifying its power with gears.


A turbine does not need a cooling system or lubricant. The air itself creates both the lubricant and the cooling mechanism. Pressurized air is thin but enough lubrication for the fins of a turbine. Since the heated air is expelled at the end of the engine, all waste heat is taken with it. A turbine runs at a continuous temperature unless the pressure is increased.


Hot air creates pressure, and it cools as that pressure is released. This means that any inconsistent heating will increase pressure and will release itself faster. Since a hot turbine requires less fuel, the computer-controlled fuel injection will respond accordingly. Gas turbines are small because they do not require many supporting systems.


A gas filter means a strainer for incoming air. Regular car engines use an air filter to screen the air for microscopic particles that could build up or scratch the walls of the combustion chamber. Purified air prolongs the life of the engine. The same is true of turbine engines. While combustion is simple, the resulting hot air could contain mineral particles that could scratch and wear the turbine. A gas filter prevents this.


Gas turbine filters are made the same as other air filters. The fabric must be manufactured from a material that is able to trap microscopic particles. That material might be fiberglass, since that is also strong and able to withstand the strong suction force of some gas turbines. The filter needs a supporting frame, which is assembled in a factory.


Gas filters are one of the few supporting systems that a combustion turbine requires. It is essential for quality and longevity, and it is a good idea to replace them according to schedule. Industrial equipment is expensive, and a gas turbine for a rotary kiln is a specialized piece of equipment. Replacement parts are likely rare and expensive.